Artefactual incidence of ̇VO2 plateau and ̇VO2 max in historical studies

Purpose: Contemporary understanding of the time course of oxygen uptake suggests that traditional discontinuous tests are of insufficient duration to elicit a fully developed V˙O₂ response. However, this remains to be empirically demonstrated. Thus, the aims of the present study were: (1) to investigate whether early V˙O_2max assessments underestimated actual V˙O₂, and (2) to investigate whether the apparent V˙O₂ plateau observed in classic studies was an artefact of measuring in a non-steady state. Summary of facts and results: Twelve males (age 28 ± 7 y, 1.78 ± 0.05 m, 80 ± 11 kg) each completed a constant speed discontinuous test. The study design replicated the increasing gradient discontinuous test used by Tayloret al. (1955). V˙O₂ data were averaged during the 1.75–2.75 min V˙O_2.Taylor time point and the final minute of each test V˙O_2.Final. A paired samples t-test was used to evaluate differences in V˙O_2peak.Taylor and V˙O_2peak.Final. The V˙O_2peak.Final was found to be significantly higher than V˙O_2peak.Taylor (P < 0.001, d = 1.18). The slope of the V˙O₂ response, calculated from the last completed gradient for each participant was significantly different from zero during the 1.75–2.75 min (Taylor: P = 0.009, d = 1.58; final: P = 0.02, d = 0.29). Conclusion: V˙O₂ plateau in historical studies was artefactual. Further investigation, without the fallacious assumptions of historical studies, may enable exercise physiologists and practitioners to determine which combination of exercise protocol and method of data acquisition is most conducive to elicit and detect a V˙O₂ plateau.